Stockholders' Equity - 2019 Equity Financing - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 01, 2019	Jan. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
At-the-Market Offering [Member]
Class of Stock [Line Items]
Common stock shares maximum aggregate offering price		$ 20,000,000.0
Stock issuances, sales agent commission maximum percentage		3.00%
Common stock issued			0	0	0	0
2019 Equity Financing [Member] | Share Offering [Member]
Class of Stock [Line Items]
Common stock issued	10,526,500
Price per share	$ 1.90
Gross proceeds from issuance of common stock	$ 20,000,000.0
Share issuance costs	$ 1,700,000